This invention relates to conference units for use in telephone systems and more particularly to digital conference units employed in telephone systems.
U.S. Pat. No. 3,883,697, whose disclosure is incorporated herein by reference, and the copending application of A. F. Presto, J. G. Dunn and T. C. Chen, Ser. No. 489,574, filed Jul. 18, 1974, now U.S. Pat. No. 3,937,898, whose disclosure is incorporated herein by reference, each disclose a digital conference unit (DCU) that operates as a conference bridge so that at any node in the telephone system the conference bridge is capable of connecting local or remote subscribers into a conference. These prior art DCUs both employ delta modulation.